This research program is directed to the attainment of optimal healing of arterial prostheses in man. The flow surface of such prostheses will be smooth, uniform, from 50 to 150 microns thick and completely covered by endothelium. We believe that prostheses that can be healed in this manner will be suitable for use even in small arteries and across the knee joint. To attain this goal, research will be directed toward: 1) Determination of the influence of prosthesis design, duration of implantation and of type and degree of healing upon the thrombogenicity of the flow surface; 2) Ascertainment of the specific rheologic conditions required to prevent thrombus buildup upon flow surfaces of known thrombogenicity; and 3) Development of new arterial prostheses that will provide maximum assistance to the healing process and be suitable for use even for the coronary arteries.